Update CHANGELOG due to the introduction of !5620

CHANGELOG

@@ -21,7 +21,7 @@ v 8.11.0 (unreleased)
   - Optimize checking if a user has read access to a list of issues !5370
   - Nokogiri's various parsing methods are now instrumented
   - Add a way to send an email and create an issue based on private personal token. Find the email address from issues page. !3363
-  - Add pipeline events and a corresponding Slack integration !5525
+  - Add pipeline events to Slack integration !5525
   - Include old revision in merge request update hooks (Ben Boeckel)
   - Add build event color in HipChat messages (David Eisner)
   - Make fork counter always clickable. !5463 (winniehell)